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Thoughts on power factor and DC windings
Thoughts on power factor and DC windings
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Old 18th June 2018, 10:24 AM   #51
trobbins is offline trobbins  Australia
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Tony, I'm hoping your PF value for class AB at idle is higher than PF value when thrashing the speaker. That is consistent with the mains AC current pulses being a higher peak amplitude, and higher crest factor, when supplying more load power - the PF changes due to the changing distortion level of the current waveform. Jazbo's link shows that diagrammatically.
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Old 18th June 2018, 07:55 PM   #52
Elerion is offline Elerion  Spain
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This is an asc which shows how PF varies with resistance load.
Just run and check the log.


Just ignore the unconnected RC. Some testing to see how RC filter affect PF, not in use right now.
Attached Files
File Type: asc power_factor.asc (2.1 KB, 5 views)
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Old 18th June 2018, 09:37 PM   #53
TonyTecson is offline TonyTecson  Philippines
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Thoughts on power factor and DC windings
well, i got results and is okay with it...

and i know how to make my psu's, beefy with lots of filter caps, yummy.....
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Old 18th June 2018, 10:57 PM   #54
TonyTecson is offline TonyTecson  Philippines
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Thoughts on power factor and DC windings
Quote:
Originally Posted by Elerion View Post
This is an asc which shows how PF varies with resistance load.
Just run and check the log.


Just ignore the unconnected RC. Some testing to see how RC filter affect PF, not in use right now.
simulations are fun......i just do not put any faith in them....i build real psu's and real amps...
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Old 18th June 2018, 11:53 PM   #55
wg_ski is offline wg_ski  United States
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Quote:
Originally Posted by jazbo8 View Post
you can not get an accurate reading of the PF using just voltmeters and amp meters.
You can if your "current meter" could measure true RMS and had bandwidth up to about the 15th harmonic. Well, at least the 7th. Any idea where you might be able to find such an instrument?

Quote:
The discussion here is just for our own amusement.
It might also matter if you want to be sure your transformer isn't being overloaded. Especially for high draw applications like class A and tubes - where that trafo doesn't get to rest much.
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Old 19th June 2018, 12:02 AM   #56
TonyTecson is offline TonyTecson  Philippines
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Thoughts on power factor and DC windings
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Originally Posted by wg_ski View Post

It might also matter if you want to be sure your transformer isn't being overloaded. Especially for high draw applications like class A and tubes - where that trafo doesn't get to rest much.
it does matter, since i design and build all the traffos i use in my amps, this is a very easy thing for me...

and i follow PRR's advice, build it like a tank, within reason of course...
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Old 19th June 2018, 12:52 AM   #57
trobbins is offline trobbins  Australia
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Quote:
Originally Posted by wg_ski View Post
You can if your "current meter" could measure true RMS and had bandwidth up to about the 15th harmonic. Well, at least the 7th. Any idea where you might be able to find such an instrument?
Even a true rms current meter has some 'doubt' as to accuracy, especially for 'high C' filtering were the current pulse peak is relatively high and narrow, and the crest factor exceeds most meter accuracy capabilities.
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Old 19th June 2018, 12:54 AM   #58
TonyTecson is offline TonyTecson  Philippines
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Thoughts on power factor and DC windings
if we doubt everything that we do, then better not do anything at all....
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Old 19th June 2018, 03:20 AM   #59
wg_ski is offline wg_ski  United States
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Originally Posted by trobbins View Post
Even a true rms current meter has some 'doubt' as to accuracy, especially for 'high C' filtering
I think I'd trust my DSO, and the accuracy of some quick numerical integration in Excel. It really is as simple as adding up all the little time slices. Fourier? Again, Easy peasy for a computer. Phase shift at the fundamental? Can measure that with the cursors directly. I think that covers all the components needed to calculate power factor. Everything you need is already in your own back yard. Don't be afraid of a little math.
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Old 19th June 2018, 03:45 AM   #60
TonyTecson is offline TonyTecson  Philippines
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Thoughts on power factor and DC windings
how much precision do we need anyway?

the difference between having a reading and not having a reading is night and day imho...
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